This invention relates to an air bag cover assembly for concealing an air bag and, more particularly, to the retainer panel of air bag cover assembly having an air bag deployment aperture which changes in size during the various stages of air bag deployment.
It is known in motor vehicles to provide an inflatable air bag that deploys into the occupant compartment to cushion the occupant in the event of a serious crash. Such air bag systems typically include a driver air bag module mounted in the steering wheel and a passenger air bag module mounted in the instrument panel structure forward of the passenger seating position.
In mounting the passenger air bag module in the instrument panel structure it is known to provide one or more air bag deployment doors which cover the air bag deployment opening prior to air bag deployment. Often the deployment opening is formed in the instrument panel cover assembly and is covered by a totally separate air bag door that is attached to the instrument panel structure by a hinge. However, due to the separate air bag deployment door, these systems are costly.
U.S. Pat. No. 5,333,901, to William J. Barnes of General Motors Corporation, provides an instrument panel cover assembly in which the rearward (in car) portion thereof is detachably connected to the remainder of the instrument panel structure. Upon air bag deployment, the instrument panel cover assembly pivots upwardly to provide an air bag deployment opening and thus avoids the cost of a separately attached air bag deployment door.
Similar to the ""901 Patent, U.S. Pat. No. 5,755,460 also to William J. Barnes of General Motors Corporation provides an instrument panel cover assembly in which the rearward (in car) portion thereof is detachably connected to the remainder of the instrument panel structure. However, the instrument panel cover assembly also has a weakened tear seam which originates at the rearward most edge of the cover, at a point between the driver and the passenger and proceeds from the rearward edge in a generally forward direction. Upon inflation of the air bag, the passenger-side of the instrument panel cover assembly is forcibly lifted and pivoted upwardly as permitted by detachment of detachable fasteners and the tearing of the instrument panel cover assembly along the weakened tear seam.
While the ""901 and ""460 Patents provide an instrument panel cover assembly without a separately attached air bag deployment door, both instrument panel cover assemblies still require the additional hardware of a separately attached hinge bracket to retain the instrument panel cover assembly to the remainder of the instrument panel structure. Furthermore, xe2x80x9ctuningxe2x80x9d the detachable fasteners to release at a predetermined force is difficult and time consuming. Finally, if the detachable fasteners do not open due to improper fit between the parts or misalignment of the separate parts during the assembly process, the air bag may not deploy properly.
In addition to often providing an air bag deployment opening, the instrument panel cover assembly must provide the passenger-side occupant with a level of head impact protection in the event that the passenger-side occupant""s head strikes the instrument panel cover assembly. This is made more difficult after air bag deployment. After air bag deployment, the air bag deployment opening may remain opened, or only partially covered by the air bag deployment door, or the air bag deployment door may be deformed and positioned such that internal components of the air bag module (e.g. air bag canister housing) may be subsequently impacted by the passenger-side occupant. Consequently, in the event of a second vehicle impact after air bag deployment, the passenger-side occupant""s head may be capable of striking the internal components of the air bag module which are ordinarily concealed prior to air bag deployment.
What is needed is an instrument panel cover assembly providing an air bag deployment aperture that does not require covering by a separately attached air bag deployment door. What is also needed is an instrument panel cover assembly which does not require complicated hardware and offers a more simplistic design. What is also needed is an instrument panel cover assembly providing an air bag deployment aperture which sufficiently closes after air bag deployment to protect the passenger-side occupant from striking the internal components of the air bag module after air bag deployment in response to a second vehicle impact.
According to one aspect of the invention, an air bag cover assembly is provided comprising a retainer panel having an aperture during the deployment of an inflatable air bag for the airbag to pass through. The aperture has a cross-sectional area during air bag inflation greater than the cross-sectional area of the aperture when the air bag is deflated after being inflated.
According to another aspect of the invention, the retainer panel may be for an instrument panel cover assembly.
According to another aspect of the invention, the retainer panel may comprise a polymer material, and may further comprise a composition of polycarbonate and acrylonitrile-butadiene-styrene. According to another aspect of the invention, the polymer material may have a flexural modulus at 73xc2x0 Fahrenheit of at least 150,000 psi.
According to another aspect of the invention, the aperture may comprise an oval shape, and may further comprise an elliptical shape.
According to another aspect of the invention, the aperture may form along an air bag escape seam formed in the retainer panel. The air bag escape seam may be frangible. The air bag escape seam may also comprise at least one through-hole in the retainer panel, and the through-hole may comprise a slot shape
According to another aspect of the invention, the air bag escape seam formed in the retainer panel comprises a single line which may be straight or may be curved.
According to another aspect of the invention, the air bag escape seam formed in the retainer panel may comprise an area of reduced thickness in the retainer panel. The area of reduced thickness in the retainer panel may be formed adjacent a notch in the retainer panel, and the notch may comprise a V-shape.
According to another aspect of the invention, the air bag escape seam formed in the retainer panel may be obscured from view to vehicle occupants.
According to another aspect of the invention, the air bag escape seam formed in the retainer panel may extend substantially horizontally or substantially vertically across the retainer panel.
According to another aspect of the invention, at least a portion of the retainer panel may be covered by a foam material, and at least a portion of the foam is covered by a flexible cover layer.
According to another aspect of the invention, the retainer panel may comprise first and second portions adjacent the air bag escape seam. The first and second portions of the retainer panel adjacent the air bag escape seam may separate along the seam when the retainer panel is impacted by the inflating air bag to increase the cross-sectional area of the aperture during inflation of the air bag and thereafter close to at least partially decrease the cross-sectional area of the aperture after the air bag has at least partially passed through the aperture.
According to another aspect of the invention, a method of providing an air bag deployment aperture for an air bag cover assembly comprises providing a retainer panel, forming an aperture in the retainer panel for the deployment of an inflating air bag from an air bag module, increasing the cross-sectional area of the aperture during inflation of the air bag, and decreasing the cross-sectional area of the aperture after the air bag has at least partially passed through the aperture.
According to another aspect of the method of providing an air bag deployment aperture for an air bag cover assembly, the step of increasing the cross-sectional area of the aperture during inflation of the air bag also includes uncovering at least a portion of the air bag module, and the step of decreasing the cross-sectional area of the aperture after the air bag has at least partially passed through the aperture includes covering an uncovered portion of the air bag module with the retainer panel.
According to another aspect of the method of providing an air bag deployment aperture for an air bag cover assembly, the retainer panel comprises first and second portions adjacent an air bag escape seam, and the step of increasing the cross-sectional area of the aperture during inflation of the air bag includes separating the first and second portions of the retainer panel along the seam, and the step of decreasing the cross-sectional area of the aperture after the air bag has at least partially passed through the aperture includes closing the first and second portions of the retainer panel.